a. bross mutac meeting bnl april 2007 1 mucool overview muon cooling r&d alan bross
TRANSCRIPT
A. Bross MUTAC Meeting BNL April 2007 1
MuCool Overview
Muon Cooling R&DAlan Bross
A. Bross MUTAC Meeting BNL April 2007 2
Outline
MuCool Overview AB Collaboration MuCool Test Area Program Synopsis
MTA RF Program Derun Li 805 MHz program
Pillbox cavity Button cell High Pressure Gas filled Test Cell (Muons Inc.)
201 MHz program
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MuCool
Consists of 10 institutions from the US, UK and Japan
RF DevelopmentANLCockcroft InstituteFermilabIITJLABLBNLMississippi
Absorber R&DFermilabIITKEKNIUMississippiOsaka
SolenoidsLBNLMississippi
Mission Design, prototype and test all cooling channel components
201 MHz RF Cavities, LH2 absorbers, SC solenoids Support MICE (cooling demonstration experiment) Perform high beam-power engineering test of cooling
section components
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MuCool Test Area
Facility to test all components of cooling channel (not a test of ionization cooling)
At high proton beam power Designed to accommodate full Linac Proton Beam Power 1.6 X 1013
p/pulse @15 Hz – 2.4 X 1014 p/s
– 600 W into 35 cm LH2 absorber @ 400 MeV
RF power from Linac (201 and 805 MHz test stands) Waveguides pipe power to MTA
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MTA Hall
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MTA
The MTA is the focus of our Activities
RF testing (805 and 201 MHz)
High pressure H2 gas-filled RF
LH2 Absorber tests High Intensity Proton
Beam Will start with low
intensity
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MTA Hall Instrumentation
805
201
CsI
Plastic Scintillator
Magnet
Chipmunk
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RF Cavity R and D
ANL/FNAL/IIT/LBNL/UMiss
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RF R&D Program
Basic Questions: Can we do anything to make MICE work better? How does magnetic field affect rf cavities” What materials and material properties are desirable? What surface modification is possible? NF and Muon Colliders also require SCRF, Can we
optimize this? Accomplishments
Better understanding of conditioning with magnetic field in 805 cavity.
Full gradient operation of 201 MHz cavity in solenoid fringe field
Installation of Be windows and button test assembly. Better modeling of breakdown limits. Involvement with SCRF and material science community
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RF R&D Program II
Major papers: X ray Spectra, Nucl. Instrum. Meth. Phys. Rev. A. 472, 600 (2001)
http://www-mucool.fnal.gov/mcnotes/public/pdf/muc0139/muc0139.pdf Measurements of x-rays from a single cell cavity
Open Cell Cavity, Phys. Rev. STAB 6, 072001 (2003) http://link.aps.org/doi/10.1103/PhysRevSTAB.6.072001 Measurements of 6 cell cavity, dark current measurements, w/wo B
fields, comp. with other cavities, tensile stress Cluster emission, Phys. Rev. STAB 7, 122001 (2004)
http://link.aps.org/doi/10.1103/PhysRevSTAB.7.122001 Emission of clusters, thermal and field dependence,
Breakdown mechanics, Nucl. Instrum. and Meth A 537, 510, (2005) http://www-mucool.fnal.gov/mcnotes/public/pdf/muc0286/muc0286.pdf General theory of tensile stress triggered breakdown
Magnetic fields, Phys. Rev. STAB 8, 072001 (2005) http://link.aps.org/doi/10.1103/PhysRevSTAB.8.072001 Measurements with 805 MHz pillbox, measurement of s2(b)
Surface damage, Phys. Rev. STAB 9, 062001 (2006) http://link.aps.org/doi/10.1103/PhysRevSTAB.9.062001 Relationship between surface damage and maximum operating fields.
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Fundamental Focus Of RF R&D
Study the limits on Accelerating Gradient in NCRF cavities in magnetic field
We believe that the behavior of RF systems in general can be accurately described (predicted) by universal curves
This applies to all accelerating structures
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805 MHz
Data seem to follow universal curve
Max stable gradient degrades quickly with B field
Remeasured Same results Does not condition
Gra
die
nt
in M
V/m
Peak Magnetic Field in T at the Window
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RF R&D – 201 MHz Cavity Design
The 201 MHz Cavity – 16 MV/m Gradient Achieved New data on x-ray backgrounds will be presented
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Absorber R and D
IIT/KEK/NIU/Osaka/UMiss
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2D Transverse Cooling
and
Figure of merit: M=LRdE/ds
M2 (4D cooling) for different absorbers
Absorber Design Issues
Absorber Accelerator
Momentum loss is opposite to motion, p, p x , p y , E decrease
Momentum gain is purely longitudinal
Large emittance
Small emittance
H2 is clearly Best -Neglecting Engineering
Issues Windows, Safety
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Convective Absorber Activities
First Round of studies of the KEK absorber performed in the MTA
GHe used to input power
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Convective Absorber Activities II
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Convective Absorber Activities
KEK Convector Absorber upgrades
Electrical Heater New
Temperature sensors
LH liquid level sensor
Have now been installed and system has been tested
Ready for LH2 run After safety
approval
Absorber Body being modified in Lab 6 at Fermilab
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LiH Test Program
Produce encapsulating cast (not pressed) samples Small disks (5-10 cm)
Test casting procedures Examine mechanical properties Destructive tests for voids
Large disk (30 cm) for detailed thermal conductivity studies
External Cooling + Internal Heating Potential absorber for MICE Phase I
– Non-instrumented, no cooling
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SS base plateattached to vibrator
3/8” nut
High temp glass ceramic
High temp low k gasket
1” copper tube
High temp low k gasket
12” SS 316L ring
High temp glass ceramic
Thermocouples K (900C)
Cap for copper tube
Thermocouple holders
Supports
Handle
Guiding lid
Engineering Design for Large Disks
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Removable, flexible silicone cooling tube (3/8”OD, 1/16” wall)
Heater to be attached inside this tube
Thermocouples
SET UP FOR THE THERMAL TEST
Epoxy all possible exposed LiH seamsor coat the whole disc with paralene
Thermal Properties Test
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MTA Cryo-Infrastructure
We are making good progress with completion of the cryo-plant and transfer-line system.
Transfer line system parts complete Our goal is to install/commission the system this FY
(well our goal was to install last FY) Before the shutdown (August) in we can start by June
We define the beginning of the window to be when the cryo-plant is up and running (producing LHe)
After the shutdown otherwise Our current operating costs (LHe) for the MTA magnet
are $3-5k/week Fermilab is providing $100k of support for MTA
operations Will allow us to run the magnet off LHe dewars for the
remainder of FY07 if required
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Existing Dewar-Fed Cryogen System
All of this is removed New (simpler) shield
wall Will allow for easier pit
access to hall More shielding needed
for beam operations in MTA Hall
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MTA – Refrigerator RoomArtist’s Conception
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GHe, LN2
StorageHeat Exch.
Storage Area
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Compressor Room
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Refrigerator Room
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Transfer Line System
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Valve BoxPiping
Transfer Line System
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CompletedValve Box
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RefrigRoomValveCan
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XferLine
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MuCool Phase II
Cryo-Infrastructure InstallationBeam Line Installation
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MTA Beam Line
MTA
400 MeV beamline for the MTA has been designed
Under Craig Moore/Carol Johnstone
External Beams Department Engineering Design mature
Cost Safety Analysis
Linac Area and Beamline Shielding Assessment for MTA
First Phase will be low-intensity
Funded by Fermilab + NFMCC Installation group now formed
– F. Garcia (Proton source group)
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MTA Beam Line Group
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First Beam Experiments
Currently 5T magnet and 201 cavity on floor (below beam ht.)
First experiments will pitch beam down to center of magnet
Allows for early tests of gas filled cavity operation in intense beam
Very-low integrated intensity
Few full-intensity linac pulses
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Phase II
Raise equipment to beam height
Install cryo-infrastructure
Valve box Transfer lines Weld system Connect to
cryo-plant Expect 2-3
month duration with appropriate technical resources
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Addition of Coupling Coil (B field studies of 201 operation) requires the 201 MHz cavity to be rotated 180 degree
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MuCool Plans for the Coming Year
805 MHz RF studies – Buttons (with and without B field) Materials tests Surface treatment Use information from ultra-high resolution surface studies
– Local Electrode Atom Probe
201 MHz RF Conditioning in B field Install Curved Be Windows and repeat
Second round of tests with KEK convective absorber Window of opportunity is until cryo installation starts
Begin thermal and mechanical tests on cast LiH absorber prototypes
Complete MTA cryo infrastructure installation and commission system
Begin Installation of beam line components during summer shutdown